A blood vessel has been among the subjects of biometrics authentication. An authentication device that uses the blood vessel as a target of biometrics authentication is proposed: the authentication device performs a predetermined process for an image data acquired as a result of taking a picture of a finger, binarizes the image data, and performs the Hough transform (For example, Patent Document 1).
Focusing on the fact that many of the blood vessels on the image are substantially linear, the authentication device adopted the Hough transform, which can extract the blood vessel from the image according to the length of the line or the blood vessel, thereby improving the accuracy of authentication.
Patent Document 1: Japanese Patent Publication No. 2005-115615
However, if root crops, such as radish, are used instead of the finger, the authentication device might wrongly recognize tubes inside the root crops as a target of biometrics authentication (these tubes, such as vessels, sieve tubes, fascicles, are referred to as an inside-root tubes, hereinafter) because they resemble the blood vessels of a living body; then, the acquired inappropriate parameters could be processed as registration data or data to be compared with the registration data. This fact was reported in: Tsutomu Matsumoto, “Biometrics Authentication for Financial Transaction,” [online], Apr. 15, 2005, the 9th study group of the Financial Services Agency for the issues on forged cash cards, (searched Aug. 21, 2006. Accordingly, the problem is that if an image-capturing object (such as root crops, gummi candy, a print of a blood-vessel image, a dummy of a human finger) having a blood vessel-like pattern of a living body is applied as a pseudo finger, the authentication device may mistakenly recognize it.